Telephone-exchange system



Oct. 29, 1929.

o. H. WILLIFORD 1,733,569

TELEPHONE EXCHANGE SYSTEM Filed Aug. 8, 1925 2 Sheets-Sheet l ATTORNE Oct. 29, 1929. o. H. WILLIFORD 69 TELEPHONE EXCHANGE SYSTEI Filed Aug. 8, 192B 2 Sheets-Sheet 2 POLAR/2E0 ATTORNEY Patented Oct; 29, 1929 UNIT STATES PATENT I,

OSCAR H; wILLIronD, or mnenwoon'; nEwaERsE ASSIGNORTO BELLITELEBHONIG LABORATORIES, INCORPORATED, on NEW YORK, N. Y., Acoiaronarronor NEW YORK VTELETEHONELEXCHANGE SYSTEM Application filed August 8, 19281- Serial No: 298,226;

This invention relates to'telephone systems and has forits object economy in recording the use ofcentral officeequipment.

Broadly stated the invention relates to -means forprodu'ci'ng repeated momentary circuit closures from the successive prolonged closures of a plurahtyof'parallel circuits. This invention. finds specific embodiment in atelephone system in which a pluralityof trunks are served by l a 'singleoperator, and provldes meansfor counting thenumber of times calls are extended by the operator while employing the minimum amountof apparatusnot necessary to the establishment of the talking connection. VVh'en the operator "completes a'connection, ground through a resistance is connected to the peg count arrangement where the circuit extends to bat 'tery through a common resistance. One side of a condenser is connected to a point between the common resistance-and theind vidual redetailed description in connection with the attacheddrawings, in which: p

Figure 1' shoWs'a-trunk circuitfor use with a call announcer; and

Figure 2 showsthe operators equipment common to a plurality ofsuch trunks and the pe count circuit.

ane form of call announcer system is dis closed in U. S. Patent 1,277,440, granted to A. El Lundell', September 3, 1918, and a general reference is made thereto although the details thereof are not'in all cases applicable to thepresent disclosure.- Reference is also made to the application of TN. A. Rhodes, Se-

rial Numberi 203,051, filed July 2, 1927, on which disclosure the present drawings'are based.

When the subscriber at substation ini I tiates a call, his line is extended by means of line finder 101 to district selector 102 and to aregister sender 103. The subscriber then dials the number'of the wanted subscriber,v settingup a registration on the sender 103 which controls theoperationofthe district selector 102 in selecting an'idle trunk to the oflice atwhichthe subscriber is located.

Assuming tl'iat the called subscriber is located in an oflice equipped toreceive the wanted line number from a call announcer, a class registration will be set up in the sender which will cause the associatlonof'call announcer 121 withthe sender'l03. 'lVhen an idle trunk has'been selected, the sender will connect a relay across the trunkconductors in the well known manner, completing a circuit from battery through the lower winding of relay 104, lower' back contact of relay 105, lower left winding of repeating'coil' 106, and thence through district selector 102 and the relay of the sender back to the" upper left winding ofcoi-l 106, upper back contact of relay 1'05, upper winding of relay 104' to I I ground'. Relay 104 operates closing a circuit 7 from battery through the left windingof relay 107, back-contact of relay 108, toground atthe front contact of relay 104.

Relay 107 in opera-ting closesa circuit from ground through lamp 117, left front contact of rela-y 107, conductor 180,-ba-ck contact of relay 229 to battery. Lamp 117 is common't'o a plurality oftr'unksandindicates-that one of the group of trunks'has been selected at thedistant end. Relay 107' also closes a circuitfrom ground over its outer right'cQntact,

winding of relay 109 to battery. Relay 109 in operating closes a circuit from battery through the winding of relay '110, rightfront I contact ofrelay 109, right normal contact of relay i111, which is individual to theneX-t trunk of the group, conductor 112 to ground. Relays 110 and 109 extend the tip and ring conductors of the trunk, as well ascertain control conductors, to the common position equipment shown in'Fig; 2.

The equipment shown in Fig; 2 is common I to all the trunks appearing at; that particularposition and is-available only if'the operator is at the position. When the operator associates her trunk with the position by means of a jack (not shown) relay 202 operates in series with the operators transmitter and repeating coil, in turn operating relays 203 and 204 from ground over the position splitting circuit which has been omitted from the disclosure.

With relays 203 and 204 operated, the operation of relays 109 and 110 completes a circuit from battery through the lower right winding of repeating coil 106, supervisory relay 114, outer left front contact of relay which may be traced from ground at the 1 front contact of relay 104, through the right winding of relay 108, right winding of relay 107, inner left front contact of relays 109'and 110, conductor 113, inner left front contact of relay 204 to battery at the left front contact of relay 207 Relay 108 operates in this circuit'and locks through its left winding to the ground at the front contact of relay 104, opening the operating circuit of relay 107 and connecting ground to the armature of relay 114. r

Relay 207 also closes a circuit at its in ner right front contact for relay 209 which initiates the cyclic operation of relays 209 to 212; These relays form'an interrupting mechanism whereby battery and ground are intermittently connected to conductors 2'14 and 216 respectively. The first operation of relay 212 closes a circuit for relay 218 which causes the sequential operation of relays 219, 220, 222, 223 and 221 for the purpose of transmitting two short impulses oftone or zip tones to the trunk circuit from the tone coil 224 after which the operators telephone is connected to the trunk to receive the number of the wanted line from the call announcer. V

The zip tones are, of course, ineffectual in the case of a. call incoming from a dial oflice but the connection of the secondary winding of the tone coil 224 to the trunk conductors by the operation of relay 219 permits relay 114 to operate in a circuit from battery through the lower right winding of repeating coil 106, winding of relay 114, outer left front contact of relay 110, conductor 115, left front'contact of relay 203, left back contact of relay 221, left front contact. of relay 219, secondary winding of tone coil 224, the next to the inner right contact ofrelay 219, outer right back contact of relay 221, right front contact-of relay 203, conductor 116, middle left contact of relay 110, outer left contact of relay 109, upper right winding of repeating coil 106 toground. Relay 114 closes a cir cuit from battery through the winding of relay 105, front contact of relay 114, to s ground at the inner right contact of relay 108. The operation of relay 105 reverses the connection of relay 104 to the tip and ring conductors of the trunk and by reversing the polarity of the current flowing thereover prepares the sender to make call announcement. When relay 221 operates it connects the operators telephone set with the trunk and disconnects coil 224 from the winding of relay 114. Relay 114 releases in turn releasing relay 105 thus restoring the polarity of current over the trunk circuit and causing the afsecond circuit exists from battery through the right winding of relay 230, contacts of relay 207, left winding and left back contact of relay 230 to intermittent ground over conductor 216. However, relay 230 is so wound that the combined effect of the two circuits through the left winding of relay 230 just neutralizes the effect of the circuit through the right winding thereof and relay 230 remains deenergized. Relay 229 operates in the above traced circuitopening the circuit of lamp 117.

When the operator has received the number of the wanted subscriber, she operates releasekey 232, which completes a circuit from ground over key 232, outer right front contact of relay 204, left back contact of relay 230, winding of relay 206 to battery. Relay 206 locks over its frontcontact to ground at the front contact of relay 221 or the front contact of interrupter relay 212, thus insuring that relay 206 will be the last relay to release. At its left contact relay 206 opens the circuit of relay 207 in turn opening the energizing circuit of relay 108 and the holding circuit of relay 107. Relay 207 also opens the flashing circuit for lamp 119, releasing relay229 and opening the circuit of relay 230. It also opens the holding circuit of relay 218 which causes the release of relays 219, 223, and 221 in succession. As soon as relay 212 opens its contact, relay 206 releases and the position circuit is restored to normal. .lVith relay 107 released, relays 109 and 110 release and the position circuit may be used with another trunk.

The release ofrelay 107also-closes a meteriiig circuit to record the fact that a call has.

been handled atthis operators position. This circuit extends from ground at the outer right back contact of relay 107, outer right-front contact of relay 108, resistance 131, conductor 118, resistance 225, to battery. The appara-' tus for controlling the meter coinpi'isesfxcondenser 201 which is'connectcd at one terminal to battery throughresistance 225 andat the.

other terminal to ground through relay 226. Therefore, when all the trunks are idle and no current is flowing through resistance 225 the potential drop across thecondenser is the full potential of,the"centralgofiice battery.

' However,- when the above traced metering circuit is closed current flows through resistance 225 and the potential at the terminalof the condenser adjacent resistance 225 is reduced by'the potential drop due to the current the winding of relay 227 is short-circuited and relav 227 releases restorin the re ister circircuits. At busy positions where a great cuit to normal. Relay 226 is polarized so that the charging current which flows when resist- (,1 ance 181 is disconnected will not operate the, It a second call is extended to anoth meter. or trunk at this operators position, for example that indicated by the relays at the bottom of Fig. 1, resistance 132 will be connected in parallel with resistance 131. The connection of these two resistances in parallel increases the current flow through resistance 225 thus again reducing the potential at condenser 201 and causing another operation of relay 226 to record another call. Similarly the connection of additional resistances in. parallel with resistances 181 and 132 causes additional reductions of the potential at condenser 201 and further operations of relay 226.

It is therefore possible by this arrangement to momentarily andrepeatedly close a metering circuit in response to the prolonged and successive closure of a number of operating many calls might exist at the same time the trunks may be subdivided into groups and duplicates of resistance 225, condenser 201 and relay 226 provided for operating the meter. It is obvious that there can be no interference between such duplicates since the meter will be freed in less time than the operator can perform her duties.

Following the operation of release key 232 The operation of relay the operator tests the called subscribers line intheiisual ma er and if it is idle inserts ,plug 122 in the subscribers ack after which .thecalled subscriber is signaled inthe usual manner.

When the called subscriber answers, a circuit is again provided forsupervisory relay 11 1 which again'operates relay and reverses the current over they trunk Conductors for any, desired supervisory purpose. The circuit remains in this condition until conversation is ended at which time the restoration of thecalled subseribers receiver releases relay 114,.releasing. relay 105 and re storing the connection of relay 10-1. "Whcn the calling subscriber restores his receiver relay 1041- releases, in turn releasing relays 108 and 128. Lamp 119 new lights steadily in series with relays 124: and 125 as a disconnect signal. I The removal of plug 122 from the jack restores relays 124 and. 125 and extinguishes lamp 119.

. What is claimed is: I

1. In a telephone system, a pluralityof pai v allel circuits, means to close one ormore of said parallel circuits for a piolongedperiodp and means.tomomentai'ily close an additional circuit each time that one ofsaid parallel circuits is closed comprisinga condenser, means in sa d parallel circuits to discharge said condenser, and means responsive to said condenser discharge to close said additional circuit; fl I, i

. 2. Ina telephone parallel circuits, means to close oi eor more of said parallel circuits for a prolonged period, aiidin eansjto momentarily close an additional" circuiteach time that one of said parallel circuits is closed comprising a condensenineans in each paralleloircuit to partially discharge said condenser, and means responsive only durin said condenser discharge to close said] additional circuit; f

3211i aytelephone system, a. group oftrunk circuits, means to establish connections over ,said trunk circuits, and means to count the numberof said connections comprising a meter, acondensenmeans to establish a given potent al on oneside ofsaid condenser, means I responsive during theestablishment of a con-v nection to reduce said potential, andmeans responsive to said reduction in potential to operate said meter.

' 4. In a telephone system, a group of trunk circuits, meansto establish connections over said trunk circuits, and means to count the number of said connectionscomprising a meter, a condenser, means toestablish a given potential on one side ofsaid condenser, means respons ve during the establishment of each connection to reduce said potential, and means responsive to each reduction in potential to operate said meter once.

5. In a telephone system, a group of trunk circuits, means to establish connections over said trunk circuits, and means to count the;

system, DIui-aIlty of number of said connections comprising a meter, a condenser, means to establish a given potential on one side of said condenser, means responsive during the establishment of a connection to reduce saidpotential, and means responsive to reductions in potential and unresponsive to increases in potential to operate said meter once for each seizure of a trunk.

6. In a telephone exchange system, a plurality of trunk circuits, operators equipment, means to automatically associate said operators equipment with a trunk circuit, means for disconnecting said equipment from said trunk circuit, and means forcounting the number of connections established by an operator comprising a condenser, .means for normally establishing a particular potential on said condenser, means responsive to said disconnecting means to reduce said potential, a meter, and means responsive to said reduction to operate said meter.

7. In a telephone exchange system, aplurality of trunk circuits, operators equipment, means to automatically associate said operators equipment With a trunk circuit, operator controlled means for disconnecting said equipment from said trunk circuit, and means for counting the number of connections established by an operatorcomprisinga condenser,

means for normally establishing a particular potential on said condenser, means responsive to said disconnecting means toreduce said potential, a meter, and means responsive to said reduction to operate said meter.

8. In a telephone exchange system, a plurality of trunk circuits, operators equipment, means to automatically associate said operators equipment With a trunk circuit, means for disconnecting said equipment from said trunk circuit, and means for counting the number of connections established by an operator comprising a condenser, means for normally establishing a particular potential on complete a connection over said trunk circuit, 7

and means for counting the number of connections established by an operator comprising a condenser, means for normaly establishing a particular potential on said condenser,

JnGELDS responsive to said disconnecting means to reduce said potential, means responsiveto the disconnection of'a completed connection to increase said potential, a meter, and means responsive to said reduction in potential and unresponsive to said increase of potentialto operate said meter,

10. In a telephone exchange system, a plurality of trunk circuits, operators equipment, means to'automatically associate said operators equipment with a trunk circuit, means for disconnecting said equipment from said trunk circuit, means thereafter effective to complete a connection over said trunk circuit, and means for counting the number of connections established by an operator comprising a condenser, means for normally establishing a particular potential on said condenser, means responsive to said disconnecting means to reduce said potential means responsive to the disconnection of a completed connection to increase said potential, a meter, and a relay polarized to be responsive to said reduction in potential and unresponsive to said increase of potential to operate said meter. 7

In Witness whereof, I hereunto subscribe my name this 6th day of August, 1928.

OSCAR H. IVILLIFORD.

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